Indicating apparatus



Patented .niy at, QS@

gaat A rNnrca'rrNe APPARATUS Don C. McRae, Miami, Fla., and John V0.Franklin, Kansas City, Mo., assignors to Eclipse Aviation Corporation,East Orange, N. J., a corporation of New Jersey Application March 16,1936, Serial No. 69,232

4 Claims.

This invention relates to indicating apparatus and particularly toindicating the relationship between the rates of rotation of any two ormore continuously rotating mechanisms such as ing ternal combustionengines installed on an airplane or other craft and subject tovariations in speed.

An object of the invention is to provide an indicating system includinga synchroscope and l@ means for causing said synchroscope to assume adenite position or condition when the subjects of study, such as theinternal combustion engines above suggested, are operating insynchronism, and to display a different type of in- 15 dication whensaid engines are rotating at different speeds. y

This and other objects and advantages will appear more fully from aconsideration of the detailed description which follows, with refer- 20ence to the accompanying drawing, wherein is i1- lustrated oneembodiment of the invention. It is to be expressly understood, however,that the drawing is for the purpose of illustration only, and is notdesigned as a denition of the limits 25 of the invention, referencebeing had for this purpose to the appended claims.

` In the drawing:

Fig. 1 is a schematic representation of the invention as applied to twointernal combustion 3@ engines; and

Figs. 2, 3 and 4 show other embodiments thereof.

Referring rst to Fig. 1, reference characters D1 and T1 designaterotatable parts of the ig- 35 nition system of engine No. i and D2 andT2 designate the corresponding rotatable parts (distributor arm andtimer, respectively) of engine No. 2, the primary and secondary windingsof the induction coils being indicated at P1 and 4@ S1, P2 and S2.

Branching from the primary ignition circuits, wires 5, 6 lead to theprimary windings l, 8 respectively, of transformers having secondarywindings 9, i0 connected by leads ii, i2 the lat- 5 ter having avoltmeter or equivalent instrument inserted therein to reflect the timedifference, if any, between the peak values of the E. M. F. of circuits5 and t, which in turn coincide with the periods of interruption ofcurrent flow at the 5@ points B1 and B2 of the respective ignitiontimers.

It is intended that the windings 'l and d will have sufficiently highresistance to prevent shunting of any material amount of energy from theignition circuit; that is, even though they provide a theoreticalmomentary path to ground (i3, i4) at the moment of current interruptionat B1 and Bz, these windings l and 8 are a practical barrier to loss ofthe primary circuit current during such moment, while neverthelesseffective to indicate (through induction into the 5 secondary circuitil, i2) the timing of the interrupting of current flow in the twoignition circuits.

It follows that indicator i5 will remain steady, indicating synchronismin the speeds of engines it i and 2, when the-interrupting impulses, orbeats in circuits' 5 and t coincide to thereby produce induced currents"of equal potentials in transformer windings 9 and lil.

Fig. 2 shows a second embodiment or the ini5 vention, using a singletransformer in place of the two indicated at l and B in Fig. l. Thissingle transformer has its primary winding it connected so as to receivethe opposing pulsa- Ytions of each of the two ignition circuits, and gewhen these opposing pulsations are so synchronized as to have the eiectof nullifying one another, the result will be an absence of anypotential gradient in the circuit through the secondary winding 22 andthe indicator (voltmeter 25 or its equivalent) 23. A 'condenser 2d maybe provided to by-pass those components of the current which are notnecessary to a determination of the actual value ci the E. M. F.impulses in the meter circuit, and the fundamental 3o frequency thereof.

In Fig. 3 a lter unit is Asubstituted for 'the transformer 2l, 22 ofFig. 2, and an aural indicator 21 (head-phones, for example) for thevisual indicator 23 of Fig. 2. 'I'he lter unit may 35 include suitablyproportioned inductances and capacitors connected as shown at t@ and t;the windings 3i of Figs. 2 and 3 corresponding to the windings P1 and P2of Fig. l.

In Fig. 4 the circuit interrupters te, 3d (cor- 4@ responding to thecircuit interrupters T1 and 'Ii` of Fig. land to the circuitinterrupters t@ of Figs. 2 and 3) are placed directly in series with theprimary windings i3 of -the transformers whose secondary windings it areconnected g5 through indicator dii in the same manner as are windings dand it of Fig. l; d@ being a source of direct current corresponding toil of Fig. l. With this arrangement of Fig. d the interrupters 33, Semay be units separate and distinct 5@ from the ignition elements ofFigs. i-S, but nevertheiess rotatable in synchronism with the associatedengines (not shown, but corresponding to engines i and 2 or Fig. l).

What is claimed is:

i.. Means Jior indicating the speed relationsnipv between two engines,each equipped 'with an engine driven periodic circuit interrupter, saidmeans comprising apair of circuits including said interrupters, and asecondary circuit containing a single index element responsive 'to thedifference, if any, in the frequencies nf current interruption in saidfirst-named circuits.

2. Means for indicating the speed relationship between two engines, eachequipped with an engine driven periodic circuit interrupter, said meanscomprising a pair of circuits including said interrupters, and asecondary circuit containing a, singley index element responsive to thedifference, if any, in the frequencies of current interruption in saidfirst-named circuits and means in said secondary circuit for couplingsaid irst-named circuits to produce energization of said index element.

3. In a signaling system for indicating synnieuwe chronous operation oftwo interna combustion engines, each having an ignition system includingan ignition induction coil and primary circuit interrupter, thecombination of an electrical signal device and a circuit connecting thesignal device and both of the primary windings of 'the induction coilsin series independently of said interrupters.

i. In a signaling system for indicating the speed of operation of aninternal combustion engine having an ignition system including anignition induction coil and primary circuit interrupter therefor, thecombination of an electrical signaling device and a circuit connectingthe signaling device and the primary winding of the induction coil inseries independently of said interrupter.

JOHN C. FRANKLIN. DON C. MCRAE.

